The Kassotis family (Greek: Κασώτης) meaning "one who hails from the island of Kasos" is a Dodecanesian Phanariot noble house (Ottoman Greeks usually with noble Byzantine heritage who owned large fiefdoms and positions of power in the Ottoman Empire despite their non-muslim status) of Venetian origin which has been involved in business and politics since the early 19th century. Originally the founder of the family Georgios Zizzis was a sailor from the island of Kasos who fought in the Greek War of Independence under admiral Georgios Sachtouris. Shortly after the Battles of Samos and Gerontas in 1824 and with his family gone after the Kasos Massacre he decided to stay in Icaria and married a local woman while Sachtouris's fleet was near the island for resupplies.

According to historian Ioannis Melas in 1864, the son of Georgios Zizzis who had adopted the name Haji Theodoros Kassotis in honor of his father, was named Archon of Icaria & Fourni as the primate of the local elder council during the reign of Ottoman sultan Abdulaziz, representing the island's Rum Millet (Roman Nation) and ruling as the island's semiautonomous lord with full judicial and administrative powers. After the death of Haji Theodoros his eldest son Georgios Kassotis inherited his position along with his lands until the unification of Icaria with the Kingdom of Greece in 1912.

Haji Theodoros and his two sons Georgios and Michael were all Archons of the Ecumenical Patriarchate and were granted titles from the Eastern Orthodox Church such as that of Megas Oikonomos. After the Icarian union with Greece many members of the family moved to Athens and pursued careers in business and politics. A notable branch of the family originates from a great-grandson of Hajji Theodoros who changed his name to Kassiotis (Greek: Κασσιώτης). Georgios Kassiotis served as an officer of the Greek cavalry during World War II and later distinguished himself as a stockbroker and politician. The descendants of George Kassiotis include shipping magnates George and Athanasia Kassiotis as well as Athanasia's son Miltiadis Marinakis.